Visibility of monster attacks

Hi, I am new to Roll20 (well, I signed up years ago, but just recently started actually using it). Now I am trying to run my first campaign as a DM. To make that easier, I bought a D&D 5th edition campaign on the Marketplace, the Essentials Kit, as part of the DM Starter Bundle. So I have access to the players handbook, monster manual, and the module. So far, so good. Now I added a skeleton from the monster manual (compendium) to the adventure. And I noticed that it behaves differently than the monsters that are in the adventure. Specifically, if I use an attack action of the skeleton, the outcome is sent to chat to all players. If I use an attack action from the character sheet of a monster that came with the adventure, the outcome is whispered to the GM (me) only, and the players don't see it. I assume that the character sheets of the monsters in the adventure and in the monster manual are programmed slightly differently. Or I made some stupid blunder. Anyway, I don't really see where that is programmed, and how I would change that. Can anyone give me a pointer on how I would change a monster action to be visible to all players when I click on it? For bonus points, right now when I click on a monster action, it just gives me two attack rolls. Would it be possible to add a damage display to the output of the attack action?

The monsters in the module have been set to whisper, while your game settings have been set to roll publicly. You can change the default in your game settings if you wish, and then go into your game, into the settings tab and at the very bottom, there is a button to update the in-game settings, under "Experimental Features" This may take a few minutes to accomplish. Similarly, your game seems to be set to not roll damage and crit damage automatically. Currently, you can roll the damage after you have rolled to hit by clicking on the name of the attack in the chat output. Some folks don't like to see the damage if the attack was a miss. This is also something you can change globally, using the procedure above. Finally, you can make all of these changes on a per creature basis if you prefer, by clicking on the gear icon in the character sheet. You will find those options available to change there.

Thank you! That reply was very helpful, and I learned a lot by following your advice. I now know how to show damage only if the attack was a hit, and how to set an NPC to not whisper anymore manually. I'm still fiddling with the "experimental feature", as it only applies the game settings that it notices to be changed. So I had to change whisper to "Query Whisper", then apply it, then change whisper to "Never Whisper", and apply it again.

Shoot. I should have mentioned that quirk, but I always forget on which setting it's necessary. So, everything working OK now?

Yes, it works. "Never Whisper" didn't work, because whenever I choose that, the whisper option disappears from the experimental feature apply settings. But I tried out "Whisper Toggle", and that did toggle the whisper setting from yes to no.